Check valves are well known in a variety of industries, including the medical industry. The purpose of such units is to allow blood or other fluids, including gases and liquids, to flow in only one direction. Under normal operating conditions the flow is prevented from reversing itself.
Under certain conditions, however, back pressure may build up to a level which may cause the check valve to collapse and fail.
In the medical field, for example, check valves are used in kidney dialysis machines which filter a patient's blood of waste products and excess water, and return the blood to the body. Normally, patients would check into the hospital three times a week to have their blood artificially cleaned. Check valves used in existing in-hospital dialysis machines are normally replaced after each use. Recent development in dialysis products now allow a patient to use a home dialysis system. This enables the patient to use the dialysis machine on a daily basis to help the patient's overall health and quality of life. In some dialysis machines, the components may be sanitized in place with steam. This requires the check valve components to withstand temperatures of 85.degree. C. Many existing check valves would degrade under these high temperatures.
Check valves commonly include an inlet and outlet housing made of molded plastic and a flexible one-way or duckbill valve made of rubber or silicone. The flexible valve is aligned and secured between the housings. As fluid is passed through the check valve, a variety of conditions may cause back pressure to build up, causing the flow to attempt to reverse its direction. Existing check valves may fail due to collapse of the flexible duckbill valve, which may actually invert itself and allow the back flow of fluid to pass through the inlet. The flexible valve may also pull away from its original secured position between the housings. Accordingly, it would be desirable to have a check valve design that would withstand high back pressure spikes which commonly occur during usage.